Despite many warnings of danger, Paul saw his trip to Jerusalem as essential
to his mission.

Paul had taught that circumcision and other rituals of the
Law of Moses were not necessary for Gentile Christians, but he had not tried
to turn Jews or Jewish Christians away from their obligations under Jewish
Law. However, some Jews from Asia Minor (where Paul had spent much time) recognized
him in the temple in Jerusalem, and they exaggerated and misrepresented the
things Paul said to stir up resentment against him. They accused Paul of urging
Jews to abandon the Law of Moses and not circumcise their sons. They also falsely
accused him of profaning the temple by bringing in a Gentile. A riot followed,
and Paul ended up in the custody of the Roman Army.